Chocolate Sponge Cake with Plum Jam, Whipped Cream & Chocolate Glaze

If you love chocolate cake, whipped cream and a little fruity tang, this classic Polish W-Z Cake, also known as Wuzetka, is one you have to try.

It consists of a light cocoa sponge cake, a layer of slightly tart plum jam, a generous amount of stabilized whipped cream and a smooth dark chocolate glaze.

The combination is simple but absolutely delicious. The slightly tart plum jam balances the sweetness of the cream and chocolate, while the cocoa sponge becomes wonderfully soft after a few hours in the refrigerator.

And if you can resist eating it immediately, W-Z Cake is even better the next day. 😉

Why You’ll Love This W-Z Cake

Soft and fluffy cocoa sponge
Generous layer of whipped cream
Slightly tart plum jam
Smooth dark chocolate glaze
Easy homemade decoration
Perfect for birthdays and celebrations
Can be prepared a day ahead
Even better after chilling overnight

Ingredients

For one 25 × 35 cm (10 × 14 inch) cake

For the Cocoa Sponge Cake

9 large eggs, room temperature
225 g granulated sugar
180 g all-purpose flour
45 g unsweetened cocoa powder
1½ teaspoons baking powder
Pinch of salt

For the Whipped Cream Filling

750 ml heavy whipping cream, 30% fat, very cold
60 g powdered sugar
2 packets whipped cream stabilizer (Sahnesteif)

For the Plum Jam Layer

200–250 g plum jam
Slightly tart plum jam is best

For the Syrup

120 ml water
1–2 tablespoons lemon juice
1 teaspoon granulated sugar
1 tablespoon rum, optional, for an adults-only version

For the Chocolate Glaze

150 g dark chocolate
75 ml heavy whipping cream, 30% fat
30 g unsalted butter

Optional Decorations

Option 1 – White chocolate zigzag

A small amount of white chocolate or white cake glaze

Option 2 – Whipped cream decoration

A small amount of the prepared stabilized whipped cream

Equipment

25 × 35 cm (10 × 14 inch) rectangular baking pan
Electric hand mixer or stand mixer
Large mixing bowl
Spatula
Small saucepan
Piping bag, if using the whipped cream decoration

How to Make Polish W-Z Cake

Step 1 – Prepare the Oven and Pan

Preheat the oven to 170°C (340°F) using conventional top and bottom heat.

Line a 25 × 35 cm baking pan with parchment paper.

Make sure the eggs are at room temperature.

Step 2 – Make the Cocoa Sponge

Separate the eggs, placing the whites in a large, clean mixing bowl and the yolks in a separate bowl.

Add a pinch of salt to the egg whites.

Beat until they begin to foam.

Gradually add the sugar while continuing to beat.

Keep mixing until the egg whites are thick, glossy and very stiff.

Add the egg yolks one at a time, mixing briefly after each addition.

Step 3 – Add the Dry Ingredients

Sift together:

flour
cocoa powder
baking powder

Add the dry ingredients to the egg mixture in 2–3 batches.

Gently fold everything together using a spatula.

Do not use the mixer at this stage.

Fold just until the dry ingredients are incorporated. Overmixing can remove the air from the batter and make the sponge heavier.

Step 4 – Bake the Sponge

Pour the batter into the prepared pan and gently smooth the surface.

Bake at 170°C (340°F) for approximately 30–35 minutes.

Check the center with a wooden skewer near the end of the baking time. It should come out clean or with only a few moist crumbs attached.

Important!

Do not open the oven during the first 25 minutes.

This is especially important with a sponge cake, as opening the oven too early can cause it to collapse.

Once baked, remove the cake from the oven and allow it to cool completely.

Step 5 – Prepare the Syrup

While the sponge is cooling, prepare the syrup.

Combine:

120 ml water
1–2 tablespoons lemon juice
1 teaspoon sugar

Stir until the sugar dissolves.

If making the cake for adults only, you can add 1 tablespoon of rum.

Set aside to cool.

Step 6 – Make the Whipped Cream

Make sure the heavy cream is very cold.

Pour it into a large mixing bowl and add the powdered sugar.

Whip until the cream starts to thicken.

Near the end of whipping, add the 2 packets of Sahnesteif.

Continue whipping briefly until the cream is thick and stable.

Be careful not to overwhip.

Step 7 – Assemble the Cake

Once the cocoa sponge is completely cool, carefully cut it horizontally into two equal layers.

Place the bottom layer on a serving board or tray.

Lightly brush it with some of the syrup.

Don’t soak it too heavily — the sponge should be moist, not wet.

Spread 200–250 g plum jam evenly over the sponge.

Next, spread the entire amount of whipped cream evenly over the jam.

Place the second sponge layer on top.

Gently press it down so the layers sit evenly.

Lightly brush the top sponge with the remaining syrup.

Step 8 – Make the Chocolate Glaze

Heat 75 ml heavy cream in a small saucepan.

Do not let it boil.

Remove it from the heat.

Add the chopped dark chocolate and butter.

Let it sit for about 1 minute, then stir gently until the chocolate and butter are completely melted and the glaze is smooth and glossy.

Step 9 – Cover the Cake with Chocolate

Pour the chocolate glaze over the top of the cake.

Spread it gently and evenly using a spatula.

Try not to press too hard so you don’t disturb the whipped cream underneath.

Allow the chocolate glaze to cool and set slightly before decorating.

Optional Decoration

Option 1 – White Chocolate Zigzag

For a simple homemade decoration, melt a small amount of white chocolate or white cake glaze according to the package instructions.

Transfer it to a small piping bag or a zip-top bag with a tiny corner snipped off.

Drizzle thin lines back and forth across the chocolate glaze to create a zigzag pattern.

The lines don’t need to be perfectly even — the simple homemade look is part of the charm.

Option 2 – Whipped Cream Dollops

For a more classic cake-shop look, decorate the top with small dollops or swirls of whipped cream.

Transfer some of the stabilized whipped cream to a piping bag fitted with a star tip.

Pipe small swirls along the top of the cake, ideally one for each future slice.

This version looks especially pretty when the cake is served at a celebration.

Step 10 – Chill

Place the finished W-Z Cake in the refrigerator for at least 4–5 hours.

However, I strongly recommend leaving it in the refrigerator overnight.

This gives the sponge time to absorb the syrup and allows the plum jam, whipped cream and chocolate to come together.

The cake becomes softer and more flavorful after resting.

Tips for the Perfect W-Z Cake

Use room-temperature eggs

They whip more easily and help create a light, airy sponge.

Beat the egg whites properly

The egg whites should be thick, glossy and very stiff before you add the yolks.

Fold gently

Once you add the flour and cocoa, use a spatula rather than a mixer.

Don’t open the oven too early

Keep the oven closed for at least the first 25 minutes.

Choose slightly tart plum jam

This is important for the balance of flavors. The tartness cuts through the sweetness of the cream and chocolate.

Keep the cream cold

Very cold heavy cream whips much better and gives you a more stable filling.

Don’t skip the chilling time

The cake needs several hours in the refrigerator to develop its best texture.

Overnight is even better. ❤️

Can I Make W-Z Cake Ahead of Time?

Absolutely.

This cake is actually perfect for making the day before serving.

Prepare the entire cake and refrigerate it overnight.

The sponge becomes beautifully moist and the flavors have time to develop.

How to Store W-Z Cake

Because the cake contains whipped cream, it should always be stored in the refrigerator.

Keep it covered or in an airtight cake container.

For the best quality, enjoy within 2–3 days.

Can I Freeze W-Z Cake?

The cocoa sponge itself freezes very well.

For the best texture, I recommend freezing the sponge separately and preparing the whipped cream and chocolate topping fresh.

The texture of whipped cream can change after freezing and thawing.

What Is W-Z Cake?

W-Z Cake (Wuzetka) is a classic Polish chocolate cake made with cocoa sponge, whipped cream and usually a layer of plum jam or another slightly tart filling.

It is a nostalgic Polish dessert that has been popular for decades and can often be found in Polish bakeries and pastry shops.

The combination of chocolate, cream and fruit is simple but incredibly satisfying.

Frequently Asked Questions

Can I use another jam?

Yes. Plum jam is my favorite because its slight tartness balances the chocolate and cream, but another slightly tart jam can work too.

Can I leave out the rum?

Absolutely. The rum is completely optional.

Can I use milk chocolate for the glaze?

You can, but I recommend dark chocolate. Its slightly bitter flavor balances the sweetness of the whipped cream and plum jam much better.

Why did my sponge sink?

The most common reasons are overmixing after adding the flour, opening the oven too early, or not whipping the egg whites sufficiently.

Can I decorate the cake without white chocolate?

Of course. Small whipped cream swirls are a beautiful alternative and make the cake look very elegant.

Can I use a different pan?

You can, but the thickness of the sponge and baking time will change. The quantities in this recipe are specifically designed for a 25 × 35 cm pan.